Schedule II - Condensed Financial Information, Balance Sheets (Details) - USD ($) $ in Millions	Jun. 30, 2017	Dec. 31, 2016	Jun. 30, 2016	Dec. 31, 2015
Assets
Cash and cash equivalents	$ 3,611	$ 3,185	$ 2,454	$ 1,968
Short-term investments	138	691
Other assets	2,287	2,227
Total assets	61,738	59,360
Liabilities:
Short-term debt	141	276
Long-term debt, carrying value	4,622	4,756
Total liabilities	47,133	45,575
Shareholders Equity:
Common stock (shares issued, 296; authorized, 600)	74	74
Additional paid-in capital	2,922	2,892
Accumulated other comprehensive loss	(1,146)	(1,382)
Retained earnings	15,102	13,855
Less: treasury stock, at cost	(2,406)	(1,716)
Total shareholders' equity	14,546	13,723
Total liabilities and equity	$ 61,738	$ 59,360